551-0436-00L  Cryo-Electron Microscopic Studies of Ribosomal Complexes with Biomedically Important Viral Proteins

SemesterFrühjahrssemester 2022
DozierendeN. Ban, D. Böhringer, M. A. Leibundgut, T. Lenarcic
Periodizitätjährlich wiederkehrende Veranstaltung
LehrspracheEnglisch
KommentarNumber of participants limited to 15.

The enrolment is done by the D-BIOL study administration.


KurzbeschreibungMany viruses have evolved specialized mechanisms to hijack the host gene expression machinery and employ cellular resources to regulate viral life cycle. They accomplish this through producing non-structural proteins that can, among other things, inhibit host protein synthesis. Participants of this course will visualize ribosomes in complex with a non-structural viral protein at high resolution.
LernzielThe goal of the course is to acquire the most important techniques and methods for the purification and structural characterisation of macromolecular complexes by transmission electron microscopy. The emphasis of the course is on the special practical requirements for the application of these techniques on macromolecular structures in the MDa range.
InhaltProtein synthesis is a very energy intensive process that can consume over half the total metabolism of a cell. In eukaryotes, translation is therefore tightly regulated at the stage of initiation. Regulatory processes are much more complex at this step than in prokaryotes and a large number of RNA modification processes and translation initiation factors are required to ensure faithful initiation, elongation and termination of translation. However, several viruses may interfere with host translation by affecting the initiation step or by modifying the activity of key initiation factors to ensure an efficient translation of viral mRNA. Amongst such viruses is also SARS-CoV-2, which infects a large variety of vertebrate species. On entering host cells, the viral genomic RNA is translated by the cellular protein synthesis machinery to produce a set of non-structural proteins, which by inhibiting host translation render cell conditions favorable for viral production. Within the Ban lab, we have studied, and continue to investigate, medically relevant viral proteins. This course will involve producing and attempting to determine the structure of a non-structural viral protein in a ribosome-bound form.

A variety of purification techniques, including affinity chromatography and ultracentrifugation, will be used during the purification of macromolecular complexes. Purified assemblies will be then investigated functionally. Students will then characterise their samples structurally through transmission electron cryo-microscopy (cryo-EM), including sample preparation, microscopy, data evaluation and the calculation of densities. Finally, students will learn how to build and refine molecular models into parts of the calculated cryo-EM density. The participants will be working on a closed project related to current research within the laboratory and throughout the course the practical work will be accompanied by brief theoretical introductions. The principal aim of the course is to strengthen the skills required to independently conduct meaningful biophysical and biochemical experiments and to provide an early introduction into the structural characterisation of cellular macromolecular assemblies.
SkriptA script will be distributed at the beginning of the course that will cover the experiments to be performed, provide references to the relevant literature and suggest points for further consideration for interested students.
LiteraturLiterature
A basic overview is provided within the references below. Further reading and citations shall be detailed in the course script.
- A. Fersht, Structure and mechanism in protein science, Freeman, 1999 (Chapters 1 and 6).
- M. van Heel et al., Single-particle electron cryo microscopy: towards atomic resolution, Quart. Rev. Biophys. (33), 307-369 (2000).
Voraussetzungen / BesonderesThe course will be held in English. Students should have either completed courses:
551-0307-00L Biomolecular Structure and Mechanism I: Protein Structure and Function
551-0307-01L Biomolecular Structure and Mechanism II: Large Cellular Machines
or equivalent courses covering the structure and function of biological macromolecules.